1. Field of the Invention
The present invention relates to a vehicular lamp unit and a vehicular lamp of so-called projector-type, and particularly relates to a vehicular lamp unit and a vehicular lamp provided with a shade that forms a cut-off line of a light distribution pattern.
2. Related Art
Conventionally, as one form of a vehicular lamp such as a headlamp, a so-called projector-type vehicular lamp is known. This projector-type vehicular lamp is structured to collect and reflect light from a light source disposed on an optical axis to the front towards the optical axis using a reflector, and to radiate the reflected light to the front of the lamp via a projection lens provided in front of the reflector.
It is common that, when such a projector-type lamp unit is used as a low-beam headlamp, a shade is provided between the projection lens and the light source, and a part of the reflected light from the reflector and a part of direct light from the light source are blocked by the shade, thereby forming a cut-off line of a light distribution pattern. Therefore, for instance, the light that is incident below the reflector and blocked by the shade becomes loss of light that does not contribute to the light distribution projected forward. Particularly, when a semiconductor light-emitting element is used as the light source, an amount of radiated light is likely to be insufficient.
Accordingly, there has been proposed a projector-type lamp unit provided with a main reflector having a first reflective surface that reflects direct light from a light source to the front towards an optical axis, and a sub-reflector including a shade mechanism having a second reflective surface disposed in between a convex lens (projection lens) and the light source and formed in a generally flat shape along an optical axis of the convex lens (for instance, Patent Document 1).
With the use of such a lamp unit, by reflecting a part of reflected light from the main reflector upward using the second reflective surface of the sub-reflector, it is possible to effectively utilize the light, which is blocked and thus not used, to perform beam radiation to the lower side of a cut-off line.    [Patent Document 1] Japanese Patent Application Laid-Open (Kokai) No. JP-A-2006-107955